\#9513 \#9489 Fix crash when brim is used - the expansion of very small drops may result in empty polygon, which the support spot generator did not reflect
Fix crashes of stability alert checker, when empty print object was passed to it
Co-authored-by: supermerill <merill@free.fr>
Based on the unfinished idea of @supermerill, defining ExtrusionRole
as a bit mask of ExtrusionRoleModifier.
Because the ExtrusionRole was used for both ExtrusionEntity and
G-code export / G-code viewer, the original ExtrusionRole had to be split
to ExtrusionRole and GCodeExtrusionRole to support bitmask attributes
for the former while keeing a low number of ordinary values for the latter.
1) New region expansion code to propagate wave from a boundary
of a region inside of it.
2) get_extents() extended with a template attribute to work with
zero area data sets.
3) ClipperZUtils.hpp for handling Clipper operation with Z coordinate
(for source contour identification)
Fixes Slicing slows or hangs on "Generating Permiters 20%" cpu load is at 100% #8164
Fixes Slicing hangs on generating perimeters with thing:3565827 (30g) #3259
1) Removed virtual methods. There was not really need for them.
2) Some of the virtual methods were using conversion to Lines, which
was unnecessary and expensive.
3) Removed some nearest element search methods from Point.
Implementation of extra perimeters on steep overhangs/flat unsupported parts
Also contains:
Principal components computation over polygon area
New fast bridge direction estimation which minimizes amount of unanchored bridge endpoints
Refactored PerimeterGenerator for functional style, better constness
with the goal of calling PerimeterGenerator::process_xxx()
for each surface at once to collect its fill expolygons.
That allows computed better values in cases when the extrusion width of the first layer or for the infill differs from the extrusion width for perimeters.
Parameters min_feature_size and wall_transition_length now can be set in percentages, and then they will be calculated based on nozzle size. Old profiles with default values are forced to replace old default values with new default values in percentages.
The previous behavior didn't merge two ExtrusionPaths with the same extrusion width, and it also could merge two ExtrusionPaths with different widths, which was unintentional, and it could also possibly create visible artifacts in some cases.
Because simplification of ExtrusionLoop in GCode::extrude_loop is working on ExtrusionPath and not on whole ExtrusionLoop, so previous incorrect behavior was preventing simplification and removing small extrusions like in #8455.
